Broach for well pipe



Jan. 15, 1957 S. E. EKLUND BROACH FOR WELL PIPE Filed Nov. '10, 1952 INVENTOR. STONE E, EKLUND 6 Claims. (Cl. 29-951) This invention relates to metal cutting tools and is concerned with a novel form of broach for use inside pipes and tubes. This invention has found particular usefulness in preparing the inside surface of well pipe or tubing to receive plunger lift apparatus of the general type shown in the Knox et al. Patent No. 2,508,174, issued May 16, 1950.

Commercial pipe or tubing of the type used in wells, and particularly oil wells, varies somewhat on inside diameter, within manufacturing tolerances. The permissible variations are of no consequence when the pipe or tube is used only as an eduction tube for well fluid but when a plunger lift device is installed in the well the variations in internal diameter become important. This is true because the plunger ordinarily travels the entire length of the well tubing, from bottom to top and return, and must fit within the bore of the tubing in order to prevent loss in operating efficiency. It has been found that tight spots in the tubing prevent free travel of the plunger from end to end of the tubing.

Broaching tools of conventional form have been run into the string of tubing from the surface for the purpose of enlarging the tight spots in the tubing. Such broaching tools have been unsatisfactory however because they cannot accommodate wide variations in the amount of metal to be removed. It is not economicalto remove the tubing from the well, section by section, for broaching operations at the surface and therefore the broaching tool must be capable of operation at the end of a wire line suspended in the tubing and operated from the surface.

It is the principal object of my invention to provide a novel form of broaching tool particularly adapted for enlarging tight spots on the inside surface of a string of tubing, so that the tubing string may be successfully employed with a plunger lift device.

Another object of my invention is to provide a novel form of broaching tool, which includes a plurality of annular broaching elements spaced axially on a carrier, the broaching elements being of progressively increasing size.

Another object is to provide such a broaching tool in which the diameter of the forward end of each broachi ng element is preferably greater than the diameter of its rearward end.

Another object is to provide such a broaching element having both circumferential and inclined cutting edges, adapted to cut spiral chips and helical chips, respectively.

Other and more detailed objects and advantages will appear hereinafter.

Referring to the drawing:

Figure 1 is a side elevation, partly in section, showing a preferred embodiment of my invention.

Figure 2 is a transverse sectional view taken substantially on the lines 2-2 as shown in Figure 1.

Figure 3 is an enlarged sectional elevation of one of the broaching elements.

Figure 4 is a perspective view, partly broken away,

2,777,191 Patented Jan. 15, 1957 showing the form of chips cut from the inner surface of the pipe wall by the cutting edges of the broaching element.

Referring to the drawing, the broaching tool, generally designated 10, includes a mandrel 11 having an integral collar 12 at its upper end and provided with an externally threaded portion 13. The threaded portion 13 provides a means for connection to a knuckle joint and set of jars, not shown, which are suspended by means of a wire line, not shown. A nut 14 threaded on the lower end of the mandrel serves to clamp 21 series of broaching elements 15 and spacer collars 16 against the collar 12. The individual broaching elements 15 in the series are identical except that each is slightly larger in diameter than the broaching element immediately below it. In other words the broaching elements 15 progressively increase in size from the lower end of the mandrel 11. This effect is exaggerated in Figure 1 for purposes of illustration. The spacer collars 16 are identical. The mandrel is provided with an axial keyway 17 for reception of a series of keys 18 which serve to maintain the broaching elements 15 and spacer collars 16 in fixed re lationship on the mandrel 11.

Each of the broaching elements 15 is preferably larger on diameter at its lower end than at its upper end. This effect is exaggerated in Figure 3 for purposes of illustration. Each broaching element 15 has a generally conical outer surface 19 tapering upwardly. This surface is interrupted by a series of axially extending tapered grooves or slots 20 which are wider at their lower ends. A series of arcuate cutting edges 21 are thus formed at the lower end of each broaching element 15 and these cutting edges are relatively short in circumferential extent. In eifect the arcuate cutting edges 21 form the lower boundaries of tapered lugs 22, which define the opposing sides of the slots 20. The upper ends of the lugs 22 are defined by the arcuate edges 23 which are relatively long in circumferential extent.

The side edges of the lugs 22 are slanted to provide inclined cutting edges 24 on opposite sides of each lug 22.

The keyways in the broaching elements 15 are so disposed that alternate broaching elements in the series are circumferentially staggered. Thus, the arcuate cutting edges 21 on each broaching element are positioned directly above the slots 20 on the broaching element directly therebelow. The arcuate length of the cutting edges 21 is preferably substantially equal to the width of the slot 20 at its narrow end. The diameter of the upper end of each broaching element is smaller than the diameter of the lower end of the next higher broaching element in the series.

When the broaching tool encounters a restriction on the inside diameter of the pipe, only the larger diameter cutting elements which are in the upper part of the series engage the pipe surface if the amount of metal to be removed is very small. If a considerable restriction .is encountered however all of the broaching elements may be in operation simultaneously. The tool is driven downward into the restriction by means of the jars, not shown. from which it is suspended. The jarring action delivers hammer blows to the mandrel to drive the broaching elements forward into the restriction. A conventional form of spiral chip 25 is cut by each of the arcuate cutting edges 21 while an elongated helical chip 26 is generated by each of the inclined cutting edges 24. These helical chips pass upwardly through the various slots 20 on the broaching elements 15 in the series. The spiral chips 25 increase in diameter until they break off in the restricted space and pass upward through the slots 20 and into the annular spaces between the broaching elements 15. The series of broaching elements 15 is so designed that even with the tightest restrictions contemplated, the lowermost broaching element will remove little more from the inner surface of the pipe than that which will be subsequently removed by the successively larger elements thercabove. The resultant spiral chips 25 are therefore all of very thin material and as they pass upwardly through the grooves 29 tend to crumble or buckle rather than to wedge or clog in the narrow upper portion of said grooves. Similarly the helical chips 26 are also formed of thin material and each pair of said chips formed by a single groove 20 merge into each other and are broken off as they reach the broach element 15 thereabove, these chips therefore accumulating in the respective spaces between the elements 15. The forward portions of the inclined cutting edges 24 do more cutting than the upper portions thereof because of theexternal taper on diameter as shown clearly in Figure 3.

In operation the breaching tool is run into a string of well tubing from the surface and is carried on a knuckle joint at the lower end of a set of jars which are in turn suspended from a wire line. The device is run freely into lhe hole until a tight spot is encountered. The wire line is then reciprocatcd to actuate the jars and thereby deliver hammer blows to the broaching tool. When the tool has passed through the restriction, it is again lowered freely by means of the wire line until another restriction is encountered at which time the jarring action is repeated. When the broaching tool reaches the lower end of the tubing string, it is withdrawn from the tubing by means of the wire line. The tubing is then ready to receive the plunger lift apparatus.

Having fully described my invention, it is to be understood that I do not wish to be limited to the details herein set forth but my invention is of the full scope of the appended claims.

I claim:

1. A broaching tool for enlarging the internal diameter of a well pipe at certain places of limited extent along the length of said pipe where said diameter is less than the desired minimum diameter, comprising in combination: a carrier having a series of broaching elements fixed thereon in axially spaced relationship, each broaching element being larger on diameter than the adjoining breaching element forward in the series, each broaching element having a plurality of circumferentially spaced arcuate cutting edges at the forward end thereof and having an inclined cutting edge extending rearwardly from at least one end of each arcuate cutting edge.

2. A breaching tool for enlarging the internal diameter of a well pipe at certain places of limited extent along the length of said pipe Where said diameter is less than the desired minimum diameter, comprising in combination: a carrier having a series of breaching elements fixed thereon in axially spaced relationship. each broaching element being larger on diameter than the adjoining breaching element forward in the series, each breaching element having a plurality of circumferentially spaced arcnate cutting edges at the forward end thereof and having inclined cutting edges extending rearwardly from opposite ends of each arcuate cutting edge.

3. A broaching tool for enlarging the internal diameter of a well pipe at certain places of limited extent along the length of said pipe where said diameter is less than the Cil desired minimum diameter, comprising in combination: a carrier having a series of breaching elements fixed thereon in axially spaced relationship, each broaching element having conical outer surface interrupted by circumferentially spaced tapered grooves, and the forward end of each slot being wider than its rearward end, and each broaching element being larger on diameter than the adjoining broaching element forward in the series, each breaching element having a plurality of circumferentially spaced arcuate cutting edges at the forward end thereof and having inclined cutting edges extending along the sides of the slots from opposite ends of each arcuate cutting edge.

4. A broaching tool for enlarging the internal diameter of a Well pipe at certain places of limited extent along the length of said pipe where said diameter is less than the desired minimum diameter, comprising in combination: a carrier having a series of broaching elements fixed thereon in axially spaced relationship, the forward end of each broaching element being larger than its rearward end, and each breaching element being larger on diameter than the adjoining broaching element forward in the series, each broaching element having a plurality of circumferentially spaced arcuate cutting edges at the forward end thereof and having inclined cutting edges extending rearwardly from opposite ends of each arcuate cutting edge. the broaching elements in the series being circumferentially staggered so that each arcuatc cutting edge is axially misaligned with respect to the arcuate cutting edges on the breaching element next forward in the series.

5. A broaching element for use in enlarging the internal diameter of a well pipe at certain places of limited extent along the length of said pipe where said diameter is less than the desired minimum diameter, the broaching element having a conical outer surface interrupted by circumferentially spaced tapered grooves, the forward end of each broaching element being larger than its rearward end, and the forward end of each slot being wider than its rearward end, the broaching element having a plurality of circumferentially spaced arcuate cutting edges at the forward end thereof and having inclined cutting edges extending along the sides of the slots from opposite ends of each arcuate cutting edge.

6. A breaching element for use in enlarging the internal diameter of a well pipe at certain places of limited extent along the length of said pipe where said diameter is less than the desired minimum diameter, comprising an annular part having a plurality of axially extending tapered lugs circumferentially spaced thereon and defining tapered slots between them, the outer surfaces of the lugs con stituting the outer surface of the annular part, the small ends of the lugs being provided with an arcuate cutting edge, and each lug having inclined cutting edges extending along the sides of the lug from opposite ends of each arcuate cutting edge.

References Cited in the file of this patent UNITED STATES PATENTS 1,692,977 Devoe et al. Nov. 27, 1928 1,739,220 Forberg Dec. 10, 1929 2,292,990 Schmidt Aug. 1], i942 2,392,l72 Markstrum Jan. 1, I946 

